/*暴露*/
//隐藏
@color:pink;
@wrap:wrap;
* {
margin: 0;
padding: 0;
}

#wrap{
position: relative;
width: 300px;
height: 400px;
border: 1px solid;
margin: 0 auto;
.inner {
    position: absolute;
    left: 0;
    right: 0;
    top: 0;
    bottom: 0;
    margin: auto;
    background: @color;
    height: 100px;
    width: 100px;
    &:hover{
      background: pink;  
    } 
}
}